Turbines and other forms of commercial equipment frequently include rotating components inside or proximate to stationary components. For example, a typical gas turbine includes a compressor at the front, one or more combustors radially disposed about the middle, and a turbine at the rear. The compressor includes multiple stages of stationary vanes and rotating blades. Ambient air enters the compressor, and the stationary vanes and rotating blades progressively impart kinetic energy to the air to bring it to a highly energized state. The working fluid exits the compressor and flows to the combustors where it mixes with fuel and ignites to generate combustion gases having a high temperature and pressure. The combustion gases exit the combustors and flow through the turbine. A casing generally surrounds the turbine to contain the combustion gases as they flow through alternating stages of fixed nozzles and rotating buckets. For example, conventional turbine casings generally include one or more inner turbine shells surrounding the turbine rotor and an outer turbine shell surrounding the inner turbine shell(s). The fixed nozzles may be attached to the inner turbine shell(s) and the rotating buckets may be attached to the turbine rotor. Thus, as the combustion gases flow within the inner turbine shell(s) and through the nozzles, they are directed to the buckets, and thus the turbine rotor, to create rotation and produce work.
The clearance in the turbine between the inner turbine shell(s) and the rotating components is an important design consideration that balances efficiency and performance on the one hand with manufacturing and maintenance costs on the other hand. For example, reducing the clearance between the inner turbine shell(s) and the rotating components generally improves efficiency and performance of the turbine by reducing the amount of combustion gases that bypass the rotating buckets. However, reduced clearances may also result in additional manufacturing costs and increased maintenance costs attributed to increased rubbing, friction, or impact between the rotating components and the inner turbine shell(s).
Excessive rubbing between the rotating components and the inner turbine shell(s) may be particularly problematic during transient operations when the inner turbine shell(s) expands or contracts at a different rate than the rotating components. Specifically, during transient operations, temperature changes in the turbine produce axial and radial temperature gradients in the inner turbine shell(s), which can greatly affect the clearance between the inner turbine shell(s) and the rotating buckets.
In order to achieve tight clearances within a turbine (especially during transient operations), the inner turbine shell(s) must be properly aligned with the centerline of the turbine rotor. Some current methods for aligning the inner turbine shell(s) relative to the turbine centerline require extensive drilling and other machining to be performed in the field, which can be very labor and time intensive. Many also required sliding and gapped interfaces adding to eccentricity stack-up and dependency on friction. Moreover, these current methods often require service workers to gain access to the interior of the outer turbine shell, which may necessitate disassembly of one or more components of the turbine.
Accordingly, an alignment assembly that permits the alignment of an inner turbine shell relative to the rotor centerline to be adjusted quickly and easily would be welcomed in the technology.